You seem to have a couple concepts confused. The only Priority Club benefit that the card gives you is Platinum status. It's whether Platinum status gives you anything at a particular hotel that you need to be concerned about, not whether the card does. (There's no doubt that the card gives you Platinum status; there are grave doubts as to how useful Platinum status is except at certain hotels.)

Once you know that it's elite level of Platinum that is the key, you can search the "Please Post Your Priority Club Elite Experiences" sticky thread (at the top of this forum) for "Singapore" or "Orchard" and find search results like these:

http://www.flyertalk.com/forum/inter...l#post15353046 (starts at post 2308)

http://www.flyertalk.com/forum/inter...l#post15418057 (starts at post 2323)

Next, booking with points affects the room types you can get. But it usually does not affect the benefits you get. The benefits at the HI Orchard seem (from those posts) to be hit and miss in general, and I'd expect they'd be hit and miss on points stays too.

At hotels which have a good record of giving all Platinums breakfast, I always get the breakfast on points stays as well as paid stays. At hotels which have no consistent record of giving Platinums breakfast, it usually doesn't help to book paid vs points, unless you book a rate that includes breakfast of course (but that's generally at some ridiculous price especially if you're traveling by yourself).

At any rate, you should have also searched the Priority Club forum for "Singapore Orchard", in which case you would have found this three-page thread already about it:

http://www.flyertalk.com/forum/inter...er-thread.html

There are no true blackout dates in Priority Club, but whether the hotel will have rooms available on the dates you want is a totally separate issue. (Among other things, it may depend on what fraction of its rooms are of the type that is available for awards.)